1. Field of the Invention
The present invention relates to a film deposition method.
2. Description of the Related Art
A manufacturing process of an integrated circuit (IC) includes a process of filling a concave portion such as a trench, a via hole, a space of a line and space pattern or the like, with silicon oxide. For example, when depositing the silicon oxide in the trench by chemical vapor deposition (CVD), a phenomenon in which the thickness of the silicon oxide becomes greater near the aperture of the trench (so-called an “overhang” is formed) occurs because reaction gasses (precursor) react in a gas phase before reaching the bottom portion of the trench, or are adsorbed onto the side surface of the trench. Further, when the aperture of the trench is blocked by the silicon oxide, there may be a case in which a void is formed in the trench (see Patent Document 1, for example).
Here a film deposition method so-called “atomic layer deposition” (ALD) (or a “molecular layer deposition”: MLD) is known in which two kinds of reaction gasses, which react with each other, are alternately supplied onto the substrate to form a reaction product of the reaction gasses on the substrate. In this film deposition method, as the reaction product is formed by reacting one of the reaction gasses adsorbed onto a lower layer with the other of the reaction gasses, a film which more nearly reflects the shape of the lower layer can be formed compared with the CVD method. It means that the generation of the overhang or the void can be reduced by the ALD method.
However, in accordance with a requirement of high integration of the IC, an aspect ratio of the concave portion such as the trench or the like increases. Thus, when using the ALD method, it is required that the thickness distribution of the thin film formed in the concave portion such as the trench or the like is controlled as well as forming the thin film in the trench or the like without the void.